Microelectromechanical system (MEMS) devices comprise a relatively new technology that combines semiconductors with very small mechanical devices. MEMS devices are micro-machined sensors, actuators, and other structures that are formed by the addition, subtraction, modification, and patterning of materials using techniques originally developed for the semiconductor device/integrated circuit industry. MEMS devices are used in a variety of applications, such as in sensors for motion controllers, inkjet printers, airbags, microphones, and gyroscopes, as examples. The applications that MEMS devices are used in continue to expand and now also include applications such as mobile phones, automobiles, global positioning systems (GPS), video games, consumer electronics, automotive safety, and medical technology, as examples.
One type of smaller packaging for MEMS devices that has been developed is wafer level packaging (WLP). WLP involves packaging MEMS devices in packages that typically include a redistribution layer (RDL) that is used to fan out wiring for contact pads of the MEMS devices, so that electrical contact can be made on a larger pitch than contact pads of the MEMS devices and connections can be made to other devices or to a board in an end application, for example.
Corresponding numerals and symbols in the different figures generally refer to corresponding parts unless otherwise indicated. The figures are drawn to clearly illustrate the relevant aspects of the embodiments and are not necessarily drawn to scale.